I just went through this on Monday. I had an HR20-100 that had a 1tb drive on it and was replaced with an HR24-500. I also took a 2tb drive off my other HR24-500 and connected it to my new HR34 that was also installed.Greggbb said:
If you are connecting the drive to another HR2x, it will not reformat it. It will show up on the system and you will see all your recordings from the prior receiver, like nothing is wrong. However, you CANNOT play them. When you try to play them, you will get a message about it not being fully recorded and then will search for a fully recorded version(which it will never find of course). You can delete them with the red button but I found it to be a bit flakey. The first time I deleted them, they reappeared. I deleted them again and they have stayed deleted.
If you are taking a drive from an HR2x to an HR34, it DOES reformat the drive. In my case, it screwed it up some how to where the drive wouldn't even boot, even when it was put back on the HR24 from where it came. The HR24 did an 8 hr surface scan with no errors, but it still wouldn't boot. I had to connect it to my PC and clear all the partitions from it(as per what P Smith said). Once I did that, the HR34 then formatted it again and everything has been fine since.
As for the fastest way to clean it, I beleive you can just do a Delet everything and it will reset the drive. If you have an easy way to connect it to windows, P Smith's method of just deleting the partitions works well too.